A school custodial worker and elevator attendant has been arrested in the sexual assault of a 15-year-old girl inside a high school building elevator Monday morning, cops said.

The teen entered an elevator at Morris Educational Campus on Boston Road near East 166th Street at about 9:45 a.m. when Trevor U. Bernard, 67, grabbed the girl, held her and hugged her, police said.

When she tried to push him away, he allegedly kissed her on the left side of the neck. Then the girl managed to flee from the elevator.

Bernard was charged with endangering the welfare of a child and sexual abuse, cops said. He does not have a criminal record, according to police.

The Morris Educational Campus houses four small high schools in its building: High School for Violin and Dance, Bronx International High School, the School for Excellence, and the Morris Academy for Collaborative Study.